text: The extent of delocalization could be quantified by using Pipeks delocalization measurement. For orbitals which are highly localized, the Pipeks indexes will be very close to 1. On the other hand, for highly delocalized orbitals, the Pipek's indexes become larger.
  However, this method cannot evaluate the localization extent on each fragment. Thus, a new measurement is necessary. The fragment orbital localization index (FOLI) is defined as the square root of the fragment population over the delocalization index:
  Based on this localization index, the localization extent on each fragment can be determined. with higher FOLI, it means the extent of localization on this fragment is relatively low, vice versa. Thus, after acquiring the FOLI, the electrons in each OSLO will be assigned to the fragment with the lowest FOLI.